Refrigerating apparatus and method of operation thereof



July 6, 1937. E. PICK O 2,085,868

REFRIGERATING APPARATUS AND METHOD OF OPERATION THEREOF Original Filed Nov. 14, 1933 3 Sheets-Sheet 1 IN V EN TOR.

July 6, 1937. E. PICK 2,085,868

REFRIGERATING APPARATUS AND METHOD OF OPERATION THEREOF Original Filed Nov. 14, 1933 3 Sheets S'ne et 2 8 FIG. 5.

IN V EN TOR.

I2, I /2z-\ 133 July 6, 1937. E. PICK, 2,085,868

REFRIGERATING APPARATUS AND METHOD OF OPERATION THEREOF 5 Sheets-Sheet 5 Original Filed. Nov. 14, 1953 /58 \w ,7 I 152 /55 w ll?!) I53 [5/ a /54 I58 il\; 154 v N \I /57 /5/ m /56 /57 lla-3m Patented July 6, 1937' UNITED STATES REFRIGERATING APPARATUS AND METH- OD OF OPERATION THEREOF Eric Pick, New York, N. Y.,

assignor to Serve],

Inc., New York, N. Y., a corporation of Delaware Application November 14, 1933, ScrialNo. 698,006 Renewed May 7, 1937 17 Claims.

This invention relates to improvements in refrigerating apparatus and method of operation thereof; and it comprises integrating the operation of a refrigerating apparatus and initiating defrosting when said integral has reached a predetermined value; all as more fully hereinafter set forth and'as claimed.

Refrigerating apparatus have usually a cooler which is maintained at a temperature below the freezing temperature of water. When air carrying a proportion of water vapor corresponding to a dew point higher thanthe temperature of the cooler comes in contact with the cooler condensation takes place, and the moisture condensed on the cooler freezes. With the cooler installed in a closed cabinet, every opening of the door admits outside air while some of the chilled air escapes from the cabinet. Thus, additional water vapor is introduced into-the cabinet and eventual- 1y deposited on the cooler as frost.

A further source of moisture is in the cabinet itself when foodstuffs or other moist substances are placed therein for safekeeping. As a rule the cooler is placed near the top of the cabinet.

Air near the cooler is chilled whereby its density is increased causing it to fall to the bottom of the cabinet. Upon its travel away from the cooler the air increases in temperature and again picks up moisture when it comes in contact with moist substances. This warmer and moisture laden air rises back to the top of the cabinet due to its decreased density, and some of its moisture content is condensed on the cooler, Thus the thickness of the coating of frost or ice on the cooler gradually increases.

It is customary to defrost, the cooler periodically by interrupting the refrigerating effect which causes a gradual rise in temperature of the cooler, and when its temperature exceeds the 40 freezing temperature of water the frost melts and the resulting water drips oil. When all frost has been removed from the cooler in this manner the refrigerating effect is re-established whereby the apparatus is placed in normal operation again.

45 Users find the task of defrosting a cumbersome one, and are apt to postpone it until an excessive coating of frost has been formed. The greater the thickness of the frost layer is, the more resistance to the flow of heat it presents. Thus, an exces- 59 sive coating of frost on the cooler decreases the efliciency of the apparatus as well as increases the consumption of energy for a given refrigerating efiect. Furthermore, a longer defrosting period is required to remove a thicker frost coating, and

55 since, during a substantial portion of the defrost- (01. 62-4) a ing period the temperature is higher within the cabinet than the maximum permissible to avoid rapid deterioration of food or the like placed in the cabinet, a long defrosting period is in most cases objectionable.

When the user has no other means of determining the removal of all frost but visual inspection of the cooler he is aptto prolong the defrosting period unnecessarily, thereby carrying an undesirably high temperature for an excessive 10 Period of time which results in an accelerated deterioration of food within the cabinet.

In an attempt to overcome the disadvantages of haphazard manual control of defrosting it has been proposed to initate defrosting at regular in- 15 tervals of time, for instance once every-24 hours, and to terminate defrosting when a predetermined interval of time has elapsed since initiation. This, however, is not a satisfactory solution of the problem. In order to insure the com- 20 plete removal of all frost, the duration of the defrosting period must then be long enough to permit'melting of a maximum possible quantity of frost collected during any period of normal operation between defrostings. Consequently, if in the 25 course of any period of normal operation a quantity of frost smaller than this maximum has formed on the cooler, which is often the case, this frost will be completely melted long before the ensuing period of defrostingis terminated. It is 30 clear, therefore, that with this type of control one -of the main drawbacks of manual control is not eliminated, the excessively high temperature. of both cooler and cabinet for an unnecessarily extended portion of the defrosting period.

It is an object of this invention to provide novel and improved control means for the initiation as well as termination of defrosting at the most suitable respective times.

Another object of this invention. is a novel method of operating a refrigerating apparatus with greater convenience, economy and efliciency.

Still further objects of this invention will become apparent from the following disclosure which shows themanner in which I attain the aforementioned objects.

' I have found that when a refrigerating ,apparatus is in use under normal operating conditions, the quantity of frost. formed on the cooler is substantially in proportion to the integral of the periods of operation of an intermittently running motordriving the apparatus, or the integral of energy supplied-to the apparatus. According to my invention 1, therefore, provide automatic control means adapted to, first, integrate the periods of operation of, or the flow of energy to, a refrigerating apparatus, second, to interrupt the flow of energy when the integral has reached a predetermined total, and third, to maintain'this interruption for a suitable interval of time for the purpose of defrosting. In this manner de-' frosting is initiated when-a substantially constant and predetermined quantity of frost has formed, and the apparatus is returned, by the control means, to normal operation after a duration of defrosting sufficient to permit the melting of all frost.

In the accompanying drawings, wherein similar numerals refer to similarparts throughout the several views,

Figure l is a schematic view of my invention, partly in section, in combination with a refrigerating apparatus of the compression type;

Figure 2 is a developed view of the controller drum of Figure 1;

Figures 3 and 4 are enlarged sections taken, respectively, along lines 3-3 and 4-4 of Figure 1;

Figure 5 is a schematic view of another modification of my invention, partly in section, in combination with a refrigerating apparatus of the compression type;

Figure is a schematic view of a further.

modification of my invention, partly in section, in combination with a refrigerating apparatus of the absorption type;

Figure 11 is a section, in the plane of Figure 10, of the shut-01f valve of Figure 10;

Figure 12 is a side elevational view of the cam of Figure 10; and 4 Figures 13 and 14 are sections through the control valve of Figure 10, in the plane of Figure 10, showing the valve in two different operating positions.

It is to be noted that in the drawings actual relative proportions of the various parts have not always been maintained, the showing being more or less diagrammatic and certain details having been enlarged in the interest of greater clearness.

Referring now to Figure l, a cooler l0 within a suitably heat insulated cabinet H is part of a system of refrigeration including a compressor l2, a condenser l3 and a pressure reducing valve i4, all interconnected by pipe connections |5. The compressor |2, driven by an electric motor I6, is adapted to circulate a suitable refrigerant, such as S02, through this system. A-tray I1 is located in the cabinet beneath the cooler ||1 to collect moisture dripping from the cooler dur-.

ing defrosting. This type of refrigerating apparatus. well known to those skilled in the art, is usually equipped with thermostatic ceptrol means to maintain the temperature within'the cabinet between predetermined limits. Such-thermostatic control means, preferably of the type shown and described in the patent to McCabe No. 1,734,016, dated October 29, 1929, may comprise a temperature responsive element-l3 located in the cabinet H and having .an operating connection l9 with a snap action switch mechanism adapted, during normal operation, to close an electric circuit including the motor H5 at a predetermined high temperature of element l8, and to open the circuit at a predetermined low temperature of the element.

I provide a mechanism for the automatic control of defrosting which is shown enclosed in a casing 2|. A constant-speed auxiliary electric motor 22, preferably of the synchronous type, has its shaft 23 connected to a speed reducing unit 24 which may comprise a plurality of worms and worm gears or pairs of spur gears. Shaft 25 leaving the speed reducing unit 24 has a counter bearing 26 in the casing 2|. A friction wheel 21 is adjustably secured to shaft 25 by a set screw 28 and is adapted to drive a disk 29 at a slow and uniform speed whenever the motor 22 is energized. The disk 29 and a controller drum 30 are securely attached to a shaft 3| supported in the casing 2| by bearings 32 and 33. Four brushes 34, 35, 36 and 31 cooperate with the controller drum 30. These brushes are mounted on a bar 38 secured to the casing 2| at 39 and 40.

Conductors 4| and 42 are supplied with electric energy by a suitable source (not shown). The

conductor 4| is connected by conductor 43 with the switch mechanism 20 and by conductor 44 with brush 31. The conductor 42 is connected by conductor 45 with the main electric motor l6 and by the conductor 46 with the auxiliary electric motor 22. The four-point control switch 48 has contact point 49 connected by conductor 41 with switch mechanism 20, contact point 5|) by conductor 53 with brush 34, contact point 5| by conductor 54 with brush 35, and contact point 52 by conductor 55 with the main motor l6. Conductor 56 interconnects the brush 36 and the auxiliary electric motor 22.

As shown in Figure 3, the brush 35 has a spring 51, preferably made of phosphor-bronze, and attached by screws 58 and 5!! to a block 69 made of electrically insulating material, such as hard rubber or synthetic resin. The block 60 is secured by a set screw 6| to the bar 38 which is preferably of square cross section in order to prevent turning of the block 60 on the bar. 38, and to maintain the spring 51 firmly in contact with the controller drum 30. The conductor 54 is held in contact with the spring 51 by the head of screw 59. Brushes 34, 36 and 31 are preferably of the same construction as brush 35. v

The controller drum 30 is made of electrically insulating material, e. g. hard rubber, and carries metallic contact plates 62 and 63. The preferred shape of these contact plates is clearly shown in the developed view of the controller drum 30, illustrated in Figure 2. The contact plates 62 and 63 leave an area 64 of the controller drum 30 uncovered. One end of this area carries a ridge 65. Edge 66 of plate 62 and edge 61 of plate 63 are raised from the controller drum 30 (see Figures 3 and 4), and the plates 62 and 63 are thus electrically disconnected from each other. The raised edges 66 and 61-as well as the ridge cause a snapaction when the springs 51 of the brushes pass over them during revolution of the controller drum 30 which prevents burning of the points of contact by excessive sparking.

During revolution of the controller drum 3|) in the direction of arrow 68' (Figure 3) the brush 34 remains permanently in contact with plate 62, the brush 35 passes alternately over plate 62 and the permanently in contact with plate 63. While the brushes 34 and 31 are always left in the positions shown in the drawings, brushes 35 and 36 may be set on bar 38 to either of the extreme positions illustrated in Figure 2 by solid and dotted lines,

respectively, or to any intermediate positions, suchas shown in Figure 1. The purpose of this adjustability will be explained later.

The system illustrated in Figfires 1 to 4 operates as follows. In the position shown in Figures 1, ,3 and 4 the brush 35 has just snapped from the insulated ridge 65 on to contact plate 62. As the switch mechanism 26 closes periodically, electric current passes from the source through conductors 4| and 43, switch mechanism 26, conductor 41, switch points 49 and 56, conductor 53, brush 34, contact plate 62, brush 35, conductor 54, switch points 5| and 52, conduc tor 55, main motor l6, and conductors 45 and 42 back to the source. The main motor l6 runs and produces a refrigerating effect in the cooler l6. There is a continuous flow of current from the source through conductors 4| and 44, brush 31, contact plate 63, brush 36,-conductor 56, auxiliary motor 22, and conductors 46 and 42 back to the source. This maintains the auxiliary motor in continuous operationuntil it has advanced the controller drum 36 to the position in which brush 36 snaps from the edge 61 of plate 63 on to plate 62, breaking the last named circuit. The contact of brush 36 with plate 62 places the auxiliary motor 22 in parallel electric connection with the main motor "5, and both motors in elecnism 26. Both motors run now whenever the thermostatic switch' mechanism 26 completes the circuit, motor |6 producing a refrigerating effect, and auxiliary motor 22 integrating the operating periods of motor 6 in the advancing of the controller drum 36. Operation continues in this manner until the drum 36 has been turned to the position wherein brush 36 snaps from the edge 66-of plate 62 on to plate 63, causing the auxiliary motor 22 to run continuously, while the main motor remains under the control of switch mechanism 26. After a further, now more rapid advancement of drum 36 brush 35 snaps from the edge 66 of plate 62 on to the insulated area 64 whereby the circuit for the main motor I6 is interrupted, regardless of the action of switch mechanism 26. Defrosting takes place while the circuit for the main motor l6 remains interrupted for a period of time determined by the continuous operation of the auxiliary motor .22. When the latter has further advanced controller drum 36 back to the position illustrated in Figure 1, the brush 35 snaps from the insulated ridge 65 V on to plate 62, re-establishing connection for the main motor l6 under control of the switch mechanism 26 whereupon refrigerating operation is resumed. This cycle of operations is repeated as long as the control switch 48 remains in the position shown in Figure 1.

By turning the control switch 48 through 90 from the position shown in Figure 1, connection is established between the contact points 49 and 52, and between the contact points 56 and 5|. This places the inain motor l6 and the thermostatic switch mechanism 26 in direct electric series connection, by-passing the controller drum 36 and rendering the automatic control of defrosting inoperative. The refrigerating apparatus is thus in permanent operation under control of the thermostatic switch mechanism 26, the current flowing from the source through conductors 4| and 43, switch 26, conductor 41, contact points 49 and'52, conductor 55, main motor l6, and conductors 45 and 42 back to the source. Defrosting may then be carried outunder manuthrough 45 in which position all four contact points are disconnected from each other and the circuit for the main motor I6 is interrupted. The apparatus is then returned to normal refrigerating operation by.turning the control switch 48 again through 45 after a period of defrosting or shut-down determined according to the judgment of the operator..

It is to be noted that" the auxiliary electric motor 22 is not controlled by the control switch 48 while brush 36 contacts the plate 63. Therefore, if the controller drum is in defrosting position its movement by auxiliary motor, 22 cannot be stopped by any minipulation of the control switch 48, and the controller drum 36 is automatically advancedto the position wherein brush 36 has snapped from edge 61 of plate 63 on to contact plate 62. This places the controller drum 36 in readiness for automatic control of a period of refrigerating operation.

When the brush 36 is in the position shown by solid lines in Figure 2 the auxiliary motor 22 runs continuously while the brush 36 contacts the controller drum 36 between lines A and B. Upon passing line B, the brush 36 contacts the plate 62, and the auxiliary motor 22 runs thereafter intermittently for limited periods of time whenever the thermostatic switch mechanism 26 completes the circuit. If the brush' 36 is shifted to the position shown in dotted lines the auxiliary motor 22 runs continuously while the .con-' troller" drum 36 moves between lines A and C, and the period ofnormal' operation between the periods of defrosting is thereby shortened.

Brush 35, in the position shown by solid lines in Figure 2, interrupts the circuit for the main motor |6 while the controller drum 36 turns between lines D and F. If the brush 35 is moved to the position shown by dotted lines the period of defrosting is shortened as represented by the circumferential distance EF.

The rate of rotation of the controller drum 36, during operation of auxiliary motor 22, can be decreased or increased by shifting the friction wheel 21 on shaft 25 so that it drives disk 29 nearer its periphery or nearer its center, respectively. Thus, the duration of the entire operating cycle maybe adjusted by shifting the friction wheel 21, while the durations of defrosting and of normal operation may be varied independently of "each other by the respective adjustment of brushes 35 and 36 on bar 38. In this manner the mechanism may be adjusted to so control the operation of the refrigerating apparatus as best suits any individual operating conditions.

In the modification shown in Figure 5, a speed reducing unit 1| in casing 69 is driven through belt I6 by the main electric motor 6. Shaft 12 leaving the speed reducing unit H has a counter bearing 18 in the casing 69 and carries a friction wheel 14 secured by a set screw 15 and adapted to drive a disk 16 on shaft rotatably supported in bearing 16. An auxiliary constant speed motor 1!! drives in a similar manner by its shaft 86 a speed reducing unit 8| with its shaft 82 supported in a bearing 83. A friction wheel y al control by turning the control switch ,48

84, secured to shaft 82 by means of a set screw 85, is adapted to drive a disk 86 attached to a shaft 81 rotatably supported in a bearing 88. The shafts I1 and 81 carry a controller drum 89 in a manner to be described later. Brushes 90, 9| and 92 cooperate with i the controller drum 89 and are mounted on a bracket 93 made of electrically insulating material and attached to the casing 69 and 94 and 95.

Conductors 96 and 99 are connected to a source of electric energy (not shown). The conductor 96 is connected by conductor 91 with the thermostatic switch mechanism 20 and by conductor 98 with the auxiliary electric motor I9. The conductor 99 leads to contact point IOI of a control switch I00 which has a second contact point I02 connected by conductor I04 with the brush 9|, and a third contact point I03 connected by conductor I05 with the brush 92 and by conductor I06 with the main electric motor I6. Conductor I01 connects the main electric motor I6 with the thermostatic switch mechanism 20, and a conductor I08 interconnects the auxiliary electric motor I9 with the brush 90.

The controller drum 89 is made as a hollow cylinder of electrically insulating material for instance a tube of laminated fibre, and carries contact plates I09 and H0 of the shape shown in Figure 6. The plates I09 and H0 have their respective edges III and H2 raised away from the controller drum 89 as shown in Figure 8 whereby the two plates are electrically disco n nected from each other.

As shown in Figure 7 the shaft 81 carries within drum 89 a one-way drive clutch II3 secured by the key H4. The clutch 3 has two recesses II5 fitted with balls or rollers H6 and springs III. Shaft 11 carries within drum 89a one-way drive clutch 'II3A of similar construction and secured to shaft II by a key II4A (see Fig. 5A). It will be noted that when the shaft 81 is rotated in the direction of the arrow II8 (Figure 8), the balls I I6 wedge themselves in between the recesses II 5 and the inside face of the drum 89, due to friction and-the force of the springs III, thereby establishing a driving connection. If, on the through its one-way drive clutch II3A in the direction of the arrow I I8, the balls I I 6 are forced by friction against the springs III, compressing them, and the drum 89 turns freely while oneway drive clutch I I3 stands still. In this manner the controller drum 89 may be turned in the direction of the arrow I I8 by either shaft 11 or 81 while the other shaft stands still.

During normal operation of the apparatus 11- lustrated in Figures 5 to 8 the main motor I6 turns the controller drum '89 while the brush 9| contacts plate IIO whenever the circuit is completed by the thermostatic switch mechanism 20, current flowing from the source through conductor 99, contact points IM and I02, conductor I04, brush 9|, plate IIO, brush 92, conductors I05 and I06, main motor I6. conductor I01, switch 20, and conductors 91 and 96 back tothe source. In this manner the advancement of controller drum 89 is in proportion to the integral of the time periods during which the main. motor I6 runs and produces a refrigerating effect. When the drum 89 has reached the positionillustrated the continuous operation of the auxiliary motor I9, the current flowing from the source through conductor 99, contact points IN and I02, conductor I04, brush 9|, plate I09, brush 90, conductor I08, auxiliary motor I9, and conductors 98 and 96 back to the source. The operation of .the auxiliary motor I9 advances the controller.

drum 89 until, after a time controlled period of defrosting, th brush 9| slips from plate I09 over edge I I I on to plate IIO whereupon the auxiliary motor I9 is stopped and normal refrigerating operation is resumed.

The duration of normal operation as well a the duration of defrosting may be varied independently of each other by the respectiveadjustment of the friction wheels 14 and 84 on their respective shafts I2 and 82.

If the control switch I00 is turned from the connection l0I-I02 to the connection IOII03 n the control drum 89 rotates whenever the thermostatic switch 20 completes the circuit for motor I6 without, however, exercising any control over the operation of the apparatus. Defrosting may be initiated manually by so placing switch I00 that it does not connect either pair of contact points.

In the modification illustrated in Figure 9 the control mechanism is similar to that illustrated in Figures 5 to 8, and the showing has been restricted to those details which are different. Here a second auxiliary motor I20 is provided, preferably of the type of awatt hour meter, which has a driving connection with the speed reducing unit II, the belt I0 being eliminated. -The one electric power lead I2I is connected to the thermostatic switch mechanism 20 while the other lead I22 is connected to contact point I24 of the control switch I23 which has a second contact point I25 connected by conductor I21 to brush 9|, and a third contact point I26 connected by conductors I28 and I29 to the main motor I6 and by conductor I30 to the auxiliary motor I20. Conductor I3I leading from switch mechanism 20 has a connection I32 with motor I9 and a connection I33 with motor I6. Conductor I34 leads from motor I9 to brush and conductor I35 connects the brush 92 with the auxiliary motor I20.

During refrigerating operation of the apparatus shown in Figure 9 the motor I20 is in series connection with motor I6 and integrates the energy consumption of motor I6 in the advance ment ofv drum 89. During defrosting the constant speed motor I9 drives drum 89, its current passing through the switch 20 which is closed because of the high temperature existing in cabinet II during defrosting.

If the control switch I23 is turned from the connection I24-I25 to the connection I24-I26 both motors I9 and I 20 are by-passed and only the main motor I6 operates when switch 20 completes the circuit. Defrosting may then be carried out under manual control by turning-the control switch I23 to a half-way position wherein it establishes no connection.

Referring now to'Figure 10, a condenser I4I,

.a cooler I42, an absorber I43 and a generator I40, all interconnected by pipes I44, are parts of a refrigerating apparatus of the absorption type such as more fully described in the patent to you Platen et al. No. 1,609,334, dated December '7, 1926. The cooler I42 is placed in a cabinet I45 and a tray I46 is arranged to collect frost dripping from the cooler I42. I The tray I46 may be removed and emptied. manually or it may be fitted with an overflow connection adapted to discharge to a suitable place of disposal for the waste water. a

Combustible gas is supplied by a pipe I41 leading to a control valve I5I and having a branch pipe I48 leading through an adjusting valve I49 to a pilot burner I50. As shown inFigures 13 and 14, thecontrol valve casing I5I has ports I52, I53 and I54 leading into a cylindrical bore I55. Reciprocable within bore I55 is a piston I56 with a hole I51 running through its full length. The piston I56 is connected by the piston rod I58 to a bellows I59 secured to a valve bonnet 1 I60. The space within the bellows I59 is connected by a tube I6I to a bulb I62. The space within the bellows I59, the tube 'I6I and the bulb I62 is filled with an operating fluid adapted to expand and contract with rise and fall of temperature. All connections between the last named three elements are preferably made permanent by brazing or the like in order to prevent any escape of operating fluid. The port I52 com municates with the gas supply pipe I41v and the port I53 is connected by a pipe I63 with a shutoff valve I64.

The shut-off valve casing I64 has an inlet connection I65 and an outlet connection I66, adapted to communicate with each other through port,

I61'closable by a valve disk I68 under the force exerted by a spring I69 which is retained within a cap I10 (see Figure 11). A valve stem I1I secured to thevalve disk I 68 passes through a stufling gland I12.

3 A pipe I13 communicating with the control valve port I54, and the shut-01f valve outlet I66 are connected by a nipple I14 to a gas meter I15 which has its outlet connected by a pipe I88 to a burner I89 arranged to supply heat to the generator I40.

I A shaft I16 driven by the meter I15 has a bearing I 11 in the casing I18 and carries a friction wheel I19 secured by a set screw I80. The friction wheel I19 is adapted to drive adisk I 8I secured to shaft I82 which is supported in hearing I 83 and carries at its outer end a cam I84. As shown in Figure 12, the cam I84 has a notch I85 with a sharp edge I86 at one side and an inclined face I81 at the other side. The cam I84 is adapted to control the operation of the shut-off valve I64.

During normal refrigerating operation of the apparatus illustrated in Figures 10 to 14, the control valve piston I56 is in the position shown in Figure'13 wherein port I53 is partly throttled so that gas is supplied to the burner I89 at a 'rate of flow regulated to maintain the desired refrigerating efiect, the gas flowing from the source through pipe I41, ports I52 and I53, pipe 60 I63, shut-off valve I64, nipple I 14, meter I 15, and pipe I88 to the burner I 89. The shut-off valve is kept open by the cam I84 the periphery of which depresses the valve stem HI and thereby holds the valve disk I68 unseated. If the temperature Within the cabinet I45 drops the fluid in bulb I62 contracts and the bellows, I59 likewise contracts thereby P lling the piston I56 upward and further throttling the flow of gas through port I53. If the temperature within the cabinet I 45 70 rises the piston I56 is lowered by the expansion of the fluid in bulb I62 and the flow of gas is 1 increased. Thus, the temperature within the cabinet I45 is maintainedwithin predetermined limits. The hole I51 serves to equalize thev pressure-on both sides of the piston I56 and to permit position shown in Figure 14 wherein it opens port escape of the gas within the bore I55 and below the piston I56 when the piston is being lowered. In this manner normal refrigerating operation proceeds, the gas consumption of the apparatus being integrated by themeter I15 and the cam I84 being rotated in proportion to the gas consumption. Finally, after a predetermined quantity of gas has passed through the meter I15 which quantity is adjustable by a shifting of the friction wheel I19, the notch l85passes past the stem 'I1I which slips over the sharp edge I86 thereby causing the valve disk I68 to close the port I61 under the action of the spring I69. The flow of gas to thebu'rner I89 is therebyinterrupted and defrosting proceeds.

During defrosting the temperature within the cabinet I45 gradually rises and finally, at a tem perature corresponding to the melting of all frost, the fluid within the bulb I62 has expanded to such anextent that the piston I56 reaches the I54 and permits a flow of gas from the source 5 through pipe I41, ports I52 and I54, pipes IJ3- and I14, meter I15, and pipe I88 to the burner I89. The adjusting valve I49 is originally so set that it maintains a pilot flame burning at. the burner I 50; When the flow of gas is reestablished after defrosting in the manner just explained, this pilot flame at the burner I50 lights the gas admitted to the burner I89 and normal refrigerating operation is initiated. The flow of gas through the meter I15 causes turning of the cam I84 by the meter and the inclined face I81 pushes the valve stem I1I downward thereby opening the shut-off valve I64.- The ar- 35 rangement is such that the shut-off valve I64 is opened by the cam I84 before the flow of gas has produced a refrigerating efiect sufficient to lower the temperature within the cabinet I45 to an extent which causes the piston I56 by its rise to close the port I54.

Control of defrosting according to my invention permits defrosting at frequent times and after formation of a comparatively thin coating of frost. Thus, the average thickness of frost is smaller than with haphazard manual control. Furthermore, defrosting is terminated substantially at the time when all frost, is melted and therefrigerating effect is interrupted for a minimum length of time only. This results .in improved operation and improved food preservation.

While=-I have shown several forms of my invention, it will be noted that various changes may be made therein, particularly in the type and arrangement of the control means. Adjustability of the durations of normal operation and of defrosting may be dispensed with when the operating conditions of the apparatus are known in advance. Other modifications in the details of construction and arrangement of parts will readily occur to those skilled in the art. Reference is, therefore, made to the appended claims for a definition of the'limits of my invention.

What I claim is: I

1. In a refrigerating apparatus comprising a cooler wherein a refrigerating effect is produced by a supply of energy to the apparatus, thermostatic means adapted to alternately establish and interrupt the supply of energy to the apparatus, motor driven means independent of the thermo- 70 static means and adapted to interrupt the refrigerating eifect periodically for'controlled periods, and connections for effecting movement of the -motor driven means by energy supplied under control of the thermostatic means. 75

2. In combination with a refrigerating apparatus adapted to be operated by a flow of energy and comprising a cooler, a motor, thermostatic means adapted to alternately establish and inter rupt the flow of energy to the motor, and control means driven by said motor and adapted tointerrupt the flow of energy to the apparatus after a predetermined number of revolutions of the motor.

3. In combination with a refrigerating apparatus operable by flow of energy and comprising a cooler, a motor and mechanism adapted to be driven thereby, thermostatic control means adapted to alternately establish and interrupt flow of energy to the apparatus and to maintain the motor in operation while energy flows to the apparatus, said mechanism being adapted to interrupt flow of energy to the apparatus after a predetermined number of revolutions of the motor and to subsequently re-establish flow of energy to the apparatus.

4. In combination with a refrigerating apparatus intermittently operated by a source of electricity and having a cooler, electric circuits including a thermostatic switch, an electric motor and switching mechanism driven thereby, said thermostatic switch being adapted to alternately switch on andswitch off the supply of electricity and said switching mechanism being adapted to cause operation of the motor while electricity flows to the apparatus and to interrupt the flow of electricity to the apparatus after a predetermined number of revolutions of the motor.

5. In a refrigerating apparatus driven by a main electric motor, an auxiliary electric motor, a thermostatic switch, switching mechanism adapted to be driven by the auxiliary motor, and electric connections including both said motors, the thermostatic switch and the switching mechanism, the thermostatic switch being adapted to control flow of electricity to both said motors and the switching mechanism being adapted to interrupt flow of energy to the main electric motor for a period of time determined by continuous operation of the auxiliary electric motor.

6. In a refrigerating apparatus driven by an intermittently operating main electric motor, an auxiliary electric motor, switching mechanism adapted to be driven by the auxiliary motor, electric connections including the switching mechanism and both said motors, said switching mechanism being adapted to establish a circuit including both said motors, then establish a circuit through the auxiliary motor and interrupt the circuit through the main -motor, and then again establish a circuit including both said motors.

7. In a refrigerating apparatus driven by a main electric motor, an auxiliary electric motor, switching mechanism driven by the auxiliary motor, a thermostatic switch, and electric connections including a source of electric energy, the thermostatic switch, the switching mechanism and both said motors, the switching mechanism being adapted in one position thereof to establish a circuit including the source of energy, both said motors in parallel arrangement and the thermostatic switch in series arrangement with both motors, and in another position thereof to interrupt the circuit through the main motor and to maintain a circuit including the source of energy and the auxiliary motor.

8. In a refrigerating apparatus operated by a source of energy and comprising a cooler, a thermostat adapted to alternately establish and interrupt flow of energy to the apparatus, a meter adapted to integrate energy flowing to the apparatus, means independent of said thermostat and adapted to interrupt flow of energy to the apparatus, and an operating connection between the meter and said means.

9. In a refrigerating apparatus operated by combustion of gas and comprising a cooler, a gas supply pipe, a shut-off valve in said supply pipe, :1 'gas meter in said supply pipe, and an operating connection between the meter and the shutoff valve whereby the meter is adapted to close the valve when a predetermined quantity of gas has passed through the meter.

10. In a refrigerating apparatus operated by combustion of gas and comprising a cooler, a gas supply pipe, a shut-off valve in said supply pipe, a gas meter in said supply pipe, an operating connection between the meter and the shut-01f valve whereby the meter is adapted to alternately open and close the shut-off valve when predetermined quantities of gas have passed through the meter,

a by-pass connection around the shut-off valve,

a control valve in said by-pass connection, and means for closing the control valve subsequently to the opening and prior to the closing of the shut-off valve, and for opening the control valve subsequently to the closing and prior to the opening of the shut-off valve.

11. In the combination of claim 10, a cabinet, the cooler being located in the cabinet, and a temperature responsive element located in the cabinet and adapted to actuate the means for closing and opening the control valve.

12. A method of operating a refrigerating apparatus intermittently operated by a supply of energy and having a cooler subjected to the formation of frost thereon, which comprises integrating the periods of time during which energy is supplied to the apparatus and interrupting the supply of energy to the apparatus for the purpose of effecting defrosting when the integral has reached a predetermined value.

13. A method of operating a refrigerating apparatus operated by a supply of energy and having a cooler subjected to the formation of frost thereon, which comprises integrating the supply of energy to the apparatus, and interrupting the supply of energy to the apparatus for the purpose of effecting defrosting when the integral has reached a predetermined value.

14. A method of operating a refrigerating apparatus operated by a supply of energy and having a cooler subjected to the formation of frost thereon, which comprises measuring the tem-' perature produced atthecooler, alternately supplying energy to the apparatus when said temperature has reached a predetermined high value and interrupting the supplyof energy to the apparatus when said temperature has reached 9.

limits, integrating the supply of energy to the apparatus, and interrupting the supply of energy to the apparatus for the purpose of efiecting defrosting when the integral has reached a predetermined value.

16. In combination with a. refrigerating apparatus driven by an electric motor, a switching mechanism and electric driving means therefor, said switching mechanism being adapted to alternately establish and interrupt flow of electricity' to the motor, and to maintain flow of electricity to said driving means while flow of electricity to the motor is interrupted by the switching mechanism.

17. In combination with a refrigerating apparatus driven by an electric motor, a thermostatic switch, a switching mechanism and electric driving means therefor, said switching mechanism being adapted to alternately establish one circuit including the thermostatic switch and the electric motor, and another circuit including the electric driving-means but excluding the thermo- 10 static switch and the electric motor.

-- ERIC PICK. 

